WO2008040934, WO2008068170, WO/2008/087514, WO/2009/026446, WO/2009/045440, WO/2011/011186, U.S. Pat. Nos. 8,188,138, 8,058,273, and 7,803,800 disclose histone deacetylases (HDACs) inhibitors having antitumor activities and antineurondegenerative activities.